This section provides background information related to the present disclosure which is not necessarily prior art.
The consumers of modern automotive vehicles are increasingly influenced in their purchasing decisions and in their opinions of the quality of a vehicle by their satisfaction with the vehicle's sound quality. In this regard, consumers increasingly expect the interior of the vehicle to be quiet and free of noise from the power train and drive line. Consequently, vehicle manufacturers and their suppliers are under constant pressure to reduce noise to meet the increasingly stringent expectations of consumers.
Drive line components and their integration into a vehicle typically play a significant role in sound quality of a vehicle as they can provide the forcing function that excites specific driveline, suspension and body resonances to produce noise. Since this noise can be tonal in nature, it is usually readily detected by the occupants of a vehicle regardless of other noise levels. Common driveline excitation sources can include driveline imbalance and/or run-out, fluctuations in engine torque, engine idle shake, and motion variation in the meshing gear teeth of the hypoid gear set (i.e., the pinion gear and the ring gear of a differential assembly).
Propshafts are typically employed to transmit rotary power in a drive line. Modern automotive propshafts are commonly formed of relatively thin-walled steel or aluminum tubing and as such, can be receptive to various driveline excitation sources. The various excitation sources can typically cause the propshaft to vibrate in a bending (lateral) mode, a torsion mode and a shell mode. Bending mode vibration is a phenomenon wherein energy is transmitted longitudinally along the shaft and causes the shaft to bend at one or more locations. Torsion mode vibration is a phenomenon wherein energy is transmitted tangentially through the shaft and causes the shaft to twist. Shell mode vibration is a phenomenon wherein a standing wave is transmitted circumferentially about the shaft and causes the cross-section of the shaft to deflect or bend along one or more axes.
Several techniques have been employed to attenuate vibrations in propshafts including the use of foam inserts. U.S. Pat. No. 6,752,722 to Armitage, et al. for example discloses the use of a pair of foam insert members that are inserted into a propshaft tube and located at the second bending mode anti-nodes. It is known in the art to employ a vacuum to install form inserts into a propshaft tube. The installation of the foam insert(s) into a propshaft tube can be time consuming and may not be capable of locating the foam insert(s) in as precise a manner as desired.